Curable liquid rubber compositions are commonly used as adhesives and/or sealants in the automotive industry. Depending on the intended purpose or the curable liquid rubber composition, various types of liquid rubber compositions may be used such as compositions based on various types of diene polymers and copolymers that are liquid at 25° C. The crosslinking agent for these compositions is generally sulfur or a sulfur compound. In body and paint shops, these liquid rubber compositions are typically cured at temperatures ranging from 145° C. to 190° C.
To increase the reactivity of the vulcanization and peroxide systems, coagents containing a metallic compound may be introduced into curable liquid rubber compositions. The incorporation of coagents containing a metallic compound into typical curable liquid rubber compositions for automotive and transportation applications, however, often causes a destabilization of the curable liquid rubber composition during storage at temperatures of about 40° C. or more over several weeks, resulting in an undesirable increase in the viscosity of the composition.
Accordingly, curable liquid rubber compositions containing a metallic compound and having improved stability characteristics are greatly desired.